1. Technical Field
The present invention relates to a method of fabricating a CIS or CIGS thin film.
2. Description of the Related Art
In solar cells, the efficiency with which light energy is converted into electric energy is regarded as being of the utmost importance. Increasing the conversion efficiency of solar cells is still being thoroughly researched and many investments are still being made into the development of novel materials.
Currently, there are the illustrative examples of thin-film solar cells using CIS (Copper Indium Selenium, Copper Indium Sulfur or Copper Indium Selenium Sulfur) or CIGS (Copper Indium Gallium Selenium, Copper Indium Gallium Sulfur or Copper Indium Gallium Selenium Sulfur) thin films that exhibit the greatest efficiency. A variety of techniques are known to be used to fabricate a CIS or CIGS thin film.
For example, Korean Patent No. 10-0588604 discloses a method of simply and conveniently synthesizing Cu(InxGa1-x)(SeyS1-y)2 nanoparticles adapted to fabricate a CIGS thin film used as a light absorber layer of a solar cell. In addition, a method of fabricating a CIGS thin film using screen printing is revealed in the “Thin-film CIS alloy PV materials fabricated using non-vacuum, particles-based techniques,” Thin Solid Films Vol 387, 18-22 (2001). In addition, a method of fabricating a CIGS thin film using spin coating is revealed in the “Properties of Cu(In, Ga)Se2 Thin Films Prepared by Chemical Spray Pyrolysis,” Jpn. J. Appl. Phys. Vol 38, 4997-5002, 1999. In addition, a method of fabricating a CIGS thin film using a CIGS solution precursor is known in the “A High-Efficiency Solution-Deposited Thin-Film Photovoltaic Device,” Adv. Mat, 2008, 9999, 1-6.
However, such methods of fabricating a CIGS thin film are disadvantageous because they involve limitations on how cheaply a uniform thin film can be formed using them, and it is difficult to achieve high optical efficiency.